Dose specification for 125I eye plaques has been made difficult because of errors and uncertainties in available dosimetry data, especially with regard to the effect of the gold plaque on the dose, and misperceptions regarding comparisons with 60Co eye plaque data. The proposed study would attempt to resolve these problems by performing extensive TLD and film measurements, with parallel Monte Carlo calculations, in realistic eye- and-head phantoms. The 125I seed and plaque configurations to be studied conform to a particular eye plaque design that is being used in an ongoing clinical study, the Collaborative Ocular Melanoma Study. Single-seed data acquired will be incorporated in appropriate lookup tables for computer reference in multi-seed calculations. Multiple-seed data, taken in anthropomorphic phantom, will emphasize dose to normal structures, e. g., lens and optic nerve. The 60Co plaque configurations selected for study will be those readily compared with the 125I data. Also part of the study will be concurrent efforts to develop specialized planning and evaluation computer algorithms, involving least-squares optimization and volume-dose histograms, respectively.